In the spring, moon jellyfish emerge all at once, as if blooming like flowers.

The coordinated appearance of the adult form of the animal (Aurelia aurita) is a result of a temperature-sensitive protein that acts as a "timer." The timer, set off by colder water temperatures, triggers the beginning of the jellyfish metamorphosis, scientists report January 16 in Current Biology.

Understanding the molecular triggers of moon jellyfish blooms may lead to better ways to control them, the scientists suggest.